1. Field of the Invention
The present invention relates to a scanner motor.
2. Description of the Related Art
The present invention pertains to a scanner motor which is used in an output device using optical technology, such as a laser beam printer or a scanner, so as to rotate a polygon mirror. As the market for output devices using optical technology requires miniaturization and high speed, higher performance must be provided to an actuator for driving an optical reflecting device which has as an important part thereof a polygon mirror. Especially in high-speed rotation, measures must be taken to prevent vibration and noise.
The scanner motor is the machine which is installed in a laser beam printer or the like and rotates a polygon mirror at high speed to deflect and scan optical beams emitted from a light source. In the scanner motor, the polygon mirror rotated at high speed must be fixedly mounted to the scanner motor. A conventional scanner motor is schematically shown in FIG. 4.
As shown in FIG. 4, the conventional scanner motor 10 includes a polygon mirror 11 which is provided on the upper portion of the scanner motor 10, and a spring 12 which is used to couple the polygon mirror 11 to the scanner motor 10. Such a conventional scanner motor is disclosed in Korean Patent Laid-Open Publication No. 2003-84148.
The scanner motor 10 rotates a housing shaft 13 with force between a stator (not shown) which is mounted to the outer circumference of a bearing holder (not shown) and is thus subjected to external power, and a rotor magnet 15 which is mounted to the inner circumference of the rotor case 14.
The housing shaft 13 has the polygon mirror 11 installed thereon, with the rotor case 14 mounted to the lower portion of the housing shaft 13.
The housing shaft 13 has a disc shape, with the polygon mirror 11 mounted to the housing shaft 13. A rotating shaft 16 is inserted into the central portion of the housing shaft 13 to be secured thereto. The spring 12 is pressed against the upper surface of the housing shaft 13, thus locking the upper portion of the polygon mirror 11.
The rotor case 14 is secured to the lower surface of the housing shaft 13 through caulking, and the rotor magnet 15 is mounted to the inner circumferential wall of the rotor case 14 in such a way as to face the stator (not shown).
The polygon mirror 11 is fixedly mounted to the housing shaft 13 of the scanner motor 10 in such a way as to be rotated, and reflects laser beams in a laser beam printer or the like. Here, at least part of the upper surface of the polygon mirror 11 is pressed by the spring 12 installed to the housing shaft 13 to be secured to the housing shaft 13.
The spring 12 presses the upper surface of the polygon mirror 11 so that it is secured to the housing shaft 13.
However, the scanner motor 10 constructed as described above is problematic in that the housing shaft 13 serving as the support part of the polygon mirror 11 is mechanically machined to secure the levelness of the rotating shaft 16 and the polygon mirror 11, and coupling force between the spring 12 and the polygon mirror 11 is low, so that the spring 12 and the polygon mirror 11 may be separated from the scanner motor 10 because of strong impact transmitted from the exterior.
Further, when the scanner motor 10 including the polygon mirror 11 and several parts rotates at high speed, the position of each part is changed from its original position, thus resulting in unbalanced rotation and generating vibration and noise. Moreover, as the number of parts increases, interference between parts increases, so that vibration and noise further increase during high-speed rotation.
Thus, there is an urgent need for research into a scanner motor, which minimizes the movement of the polygon mirror 11 and interference between parts during high-speed rotation and prevents unbalanced rotation, thus reducing vibration and noise, in addition to reducing manufacturing cost.